Segmented seating plates and anchoring means for a turbine power plant

ABSTRACT

The invention relates to a segmented seating plate construction for providing a positive anchor for tandem-connected low pressure turbines of a turbine-generator power plant. Rectangularly arranged seating plate segments, which are not interconnected, are provided for each low pressure turbine. In both of the opposite central seating plate segments for the central low pressure turbine, located in a tandem arrangement between two other low pressure turbines having segmented seating plates, there is provided a keyway for restraining axial movements, such as those due to thermal expansion of the turbines. Each of the central seating plate segments is securely held in position by a vertically extending anchor embedded in the concrete foundation and connected to such segment by an eccentric bushing structure.

United States Patent Coleman et al.

inventors: William H. Coleman, Broomall; Robert C. Quinn, Glen Mills;Howard L. Novak, Broomall; Jack J. Kalbach, West Chester,

all of Pa.; Seward L. Jones, Claymont,

Del. [73] Assignee: Westinghouse Electric Corporation, Pittsburgh, Pa.

[22] Filed: Dec. 3, 1970 [21] Appl. No.: 94,847

[52] U.S. C1. ..415/219, 248/19, 248/D1G. .1 [51] Int. Cl F04d 29/00,F16f 15/00, FOld 25/24 [58] Field oiSearch ..4l5/l99,2l9; 248/19, D16. 1

[56] References Cited UNITED STATES PATENTS 684,201 l0/l90l Dick..248/19 1,691,037 ll/l928 Allen... .....248/l9 2,296,184 9/1942Riisc.... ..248/19 2,463,880 3/1949 Jones ..248/D1G. 1 2,356,721 8/1944Hagemann ..248/DIG. l

1451 Apr. 25, 1972 Primary ExaminerHenry F. Raduazo Atlorney-A. T.Stratton and F. P. Lyle [57] ABSTRACT The invention relates to asegmented seating plate construction for providing a positive anchor fortandem-connected low pressure turbines of a turbine-generator powerplant. Rectangularly arranged seating plate segments, which are notinterconnected, are provided for each low pressure turbine.

15 Claims, 6 Drawing Figures PATENTEDAPR 25 m2 3. 658 ,438

SHEET 2 OF 2 FIG. 4

SEGMENTED SEATING PLATES ANDANCI'IORING MEANS FOR A TURBINE POWER PLANTBACKGROUND OF THE INVENTION In a well known and typical tandem compoundarrangement of steam turbine casings, three low pressure turbines arearranged in line and interconnected by push-pull tie beams. A generatorand exciter are disposed adjacent one of the end low pressure turbines,and an intermediate pressure turbine and high pressure turbine withintermediate bearing pedestals are disposed adjacent the other end lowpressure turbine. A steam condenser is disposed below the low pressureturbines and along the transverse centerline of the central low pressureturbine, while the axial center lines of the turbine and condenser areparallel.

In the prior art, an anchored point or point of fixity is established atthe transverse centerline of the condenser and of the central lowpressure turbine. The low pressure turbine casings respond to the sametemperature increase due to changes in the heat power cycle andgenerally the casings exhaust into the same condenser. Therefore thecasings and condensers expand uniformly in all directions. However, eachlow pressure turbine is positioned on its seating plate which is, ineffect. a one piece unit. It is made up on interconnected parts whichact as a single plate as the result of welding or doweling joints ofadjacent seating plate segments. Keys are inserted into keyways to fixthe seating plate to the central low pressure turbine and thereby tohelp prevent movement in the axial direction (parallel to the turbinerotor axis). Thus axial expansions of the central low pressure turbineare directed toward the adjoining low pressure turbine, intermediatepressure turbine and high pressure turbine in the direction of thegovernor, as well as toward the adjoining other low pressure turbine,generator and exciter in the opposite or generator direction.

Since low pressure turbines are interconnected by push-pull tie beams,axial expansion of the central low pressure turbines is translatedthereby to either of the adjoining low pressure turbines, and fromthere, and through similar tie beams in bearing pedestals, they aretranslated, in the governor direction, through the intermediate pressureand high pressure turbines. These push-pull tie beams, therefore, enablea continual axial thrust between the low pressure turbines so that axialexpansions of either of the end low pressure turbines are additive tomotions imposed on it by expansion of the central low pressure turbine.Similarly, there are other push-pull thrust members located between theend low pressure turbine and the intermediate pressure turbine, theintermediate pressure turbine and inboard pedestal, the pedestal and thehigh pressure turbine, and the high pressure turbine and the governorpedestal. Therefore, axial expansions of the turbine casings act in acumulative manner.

Likewise, there is an accumulation of the reaction forces due tofriction sliding forces between the turbines and their seating platesand between the separate pedestals and their seating plates.

Because of the cumulative expansion of the casings, there is acumulative axial thrust. Therefore the aforementioned keys and keywaysmust be capable of absorbing the total net axial thrust from axialthermal expansions or contractions of all the turbine components,including the casings and bearing pedestals.

The axial thrust or friction force arises as a result of the localcoefficient of friction between the turbine components and their seatingplates, the axial motions, and the respective normal forces (totalvertical reactions) at each location.

The seating plates resist the above-mentioned axial thrust and anchorthe turbine to the foundation in the following manner. The seatingplates are supported on a layer of grout which, in turn, is supported onthe basic turbine-generator foundation material (chiefly reinforcedconcrete).

In order to enable the seating plates to be effectivein resistingmovement of the turbine casings, the plates must resist slipping at theseating plate-to-grout interface; At this interface, there also acts aneffective coefiicient of static friction and a normal force which giverise to a stability force.

The normal force consists of three separate and distinct components (l)the low pressure turbine machinery weight; (2) the condenser weightreaction imposed on its supporting low pressure turbines, or, if anexpansion joint is employed between the turbine and the condenser withthe condenser bolted down solidly, an unbalanced pressure force acts onthe seating plate which, in turn, conveys the force to the foundation;(3) the vertical clamping forces imposed as a result of prestressing thefoundation bolts. One end of these bolts is embedded in the foundationmembers, and the other end protrudes through the seating plate. Theexposed ends are screw threaded to nuts which, when tightened, apply atensile stress to the foundation bolts, resulting in establishment of aclamping force on the seating plate, pressing it to the foundatron.

Of the three components of the normal force described above, it will beseen that the last mentioned, namely, the foundation bolt clamping, isthe only variable element. It can be varied by the degree of prestress,the diameter of the bolt. and/or the number of foundation bolts. Thedegree of prestress has been optimized as the result of many years ofsuccessful service. The diameter of the bolt has evolved to a singlestandard size which is related to commercially available concretestrength. Thus, the only controllable variable left is the number offoundation bolts. By varying the number of foundation bolts, the totalnormal force is adjusted, acting in conjunction with the static frictioncoefficient at the seating plate-to-grout interface, to provide thedesired friction stability force. Occasionally, single foundation platecannot be practically loaded with the necessary number of foundationbolts, in which event it becomes necessary to tie (such as by dowelpins, tap bolts etc.) adjacent seating plates together to obtain thecombined friction stability effect of the three low pressure turbineseating plates acting in unison.

It would be desirable to design a seating plate structure which wouldreduce the large quantity of foundation structure which would reduce thelarge quantity of foundation bolts presently required, eliminate thenecessity of tying the adjacent seating plates together while givinggreater flexibility in aligning the low pressure turbine casings, andenable the substantial cost reductions and shortening of manufacturingtime.

SUMMARY OF THE INVENTION In accordance with one embodiment of theinvention, segmented seating plates are provided for each of threeadjoining tandem-connected low pressure turbines, there being no in terconnection between the segments of the seating plates of any turbine.Keyways are provided in central seating plate segments of the centrallow pressure turbine, which segments are each positively anchored to thefoundation by a novel vertical post embedded in the concrete and which,by an eccentric connection, is fitted to he segment so as to prevent anypossible movement of the anchored segments. This arrangement eliminatesthe practice of tying the adjacent seating plates together and reducesthe installation time and costs of installing a large number offoundation bolts. Furthermore, there is greater flexibility in aligningthe low pressure turbine casings than is presently available.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 4 is a further enlarged,cross-sectional view taken along lines IVIV of FIG. 3;

FIG. is a cross-sectional view taken along lines VV of FIG. 3 and on thesame scale as FIG. 4; and

FIG. 6 is a cross-sectional view taken along lines VIVI of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly toFIG. 1 of the drawing, the letter T generally denotes a portion of acompound steam turbine-generator power plant including three lowpressure turbine units connected in tandem with each other and anchoredin accordance with the present invention. On one end of the low pressureturbines connected in tandem, is a generator and exciter and anintermediate pressure turbine and high pressure turbine are connected onthe other as well known in the art.

FIG. 1 shows a low pressure turbine unit having an outer casing 1, asecond or central low pressure turbine unit having an outer casing 2,and a third low pressure turbine unit having an outer casing 3, withtheir rotors (not shown) connected in tandem along a centrallongitudinal axis of rotation AA' (See FIGS. 1 and 2).

Low pressure turbine casings 1, 2 and 3 are supported on segment seatingplate groupings 4, 5 and 6, respectively, shown more clearly in FIG. 2.

Segmented seating plate grouping 5 comprises 12 segments 7 to 18,inclusive, made of steel in the form of rectangular blocks. An importantdistinguishing feature of the present invention, compared to seatingplates of the prior art, is that the seating plate segments for any ofthe low pressure turbines are mutually spaced and not interconnected.The seating plate segments are preferably mutually spaced on the orderof 4 inches apart.

Keyways l9 and are machined in two corresponding portions in plates 8and 14, respectively, and the foot portions 2a of the turbine 2 (FIGS.2, 5 and 6). The keyways extend in a horizontal plane which is normal tothe longitudinal axis A A. The keyways 19 and 20 are defined by the footportion 2a of the turbine 2 and the central opposed seating segments 8and 14. A key 19a is inserted horizontally into the corresponding keywayl9 and a corresponding key (not shown) is inserted into keyway 20.Keyways 19 and 20 and their respective keys receive the total net axialthrust force from axial thermal expansions or contractions of theturbo-generator unit. Normally the segments 8 and 14 of the segmentedseating plate grouping 5 are too short to securely anchor the turbine inthe manner accomplished by the external keyways in prior devices.

Assured anchorage of seating plates 8 and 14 is provided by verticallyextending anchors or posts 21 and 22 of steel (see FIG. 3) embedded inthe concrete foundation 23 as shown more clearly in FIG. 4. This assuredanchorage is important because the point of fixity of theturbo-generator unit is at seating plates 8 and 14. Such posts 21 and 22positively anchor the low pressure turbine cylinder 2 against moving ina longitudinal or axial direction (parallel to its rotor axis A- A). Theposts or anchors 21 and 22 are embedded in the concrete and duringerection of the turbine casings l, 2 and 3, the protruding ends 21a and22a of the embedded posts are machined to a diameter denoted as M inFIG. 4. There is an opening of diameter N premachined in seating plate 8(and 14).

Also there is an access hole 0 having a larger diameter than N which ismachined in the foot 2a of the low pressure casing 2 (shown in adot-and-dash outline). An eccentric anchor bushing 24, preliminarilyformed as a circular plate or disc machined to a diameter N (less asmall clearance for fitting) and of a thickness approximately equal tothe thickness of seating plate 8, is provided. After final turbinealignment, the eccentricity of the center of diameter M on the exposedend 210 of the embedded axial post 21 is measured in relation to thecenter of the bore or diameter N in the seating plate. The prefitteddisc or eccentric anchor bushing 24 is then bored to an inner diameter M(plus a small clearance for fitting) at the required eccentricity.

The eccentric anchor bushings 24 are then installed by introducing themthrough the access hole 0 in the low pressure turbine foot 20. The platesegment 8 is provided with a welded-on retaining ring or washer 25 onits bottom surface which acts to maintain the proper vertical positionof the eccentric anchor bushing 24 in relation to the seating platethickness.

Finally, to protect the alignment of the various seating plate segmentsfrom motions imposed by friction forces resulting from differentialvalues of coefficient of friction. a circumferential series of anchordiscs 26 are attached to the underside of the seating plate segments.Such anchor discs 26 are solidly embedded in the layer of grout G underthe seating plates and on the surface of concrete foundation 23 so as tointerlock the plate segments and provide the desired resistance tomotion in the horizontal plane.

Two keyways 27 and 28 (FIG. 2) are provided in the oppositely disposedsegments 17 and 11, respectively, which keyways are located in parallelalignment with the longitudinal axis AA' of the turbine-generator.Similarly, keyways 29 and 30 are provided in the segmented seating plategrouping 4 for casing 1 and keyways 31 and 32 are provided in thesegmented seating plate grouping 6 for cylinder 3, all in parallelalignment with the longitudinal turbine rotor axis AA'.

A plane B-A transverse to the longitudinal axis AA of the central lowpressure turbine contains the transverse or vertical center line 34 ofthe turbine, while transverse planes C C and D-D contain vertical jointlines 35 and 36, respectively. Separately constructed sections 42, 43and 44 are bolted together, along the vertical joint lines 35 and 36.Each section has a base portion and a cover portion. Section 43 is thecentral casing portion having a central inlet in the cover portion andsections 42 and 44 are the end casing portions. Through the baseportions of sections 42,43 and 44, the steam is exhausted downwardly tocondensing equipment (not shown), as well known in the art. The centersof the gaps between the axially directed seating plate segments 7, 8, 9,13, 14 and 15 are located approximately coincident with the abovementioned vertical planes CC and D-D. Variations in the elevationalsetting of the low pressure turbine foot adjacent casing base sectionsare readily tolerated. This allows for much less precision machining ofthe casing sections 42, 43 and 44 since each seating plate segment canbe adjusted vertically to support the corresponding casing section. Asan example, up to 0.25 inches of vertical tolerance on turbine casingsections is allowable as compared to 0.001 inches previously allowable.

It should be noted that each of the seating plate segments 7 to 18,inclusive, is independently set to an elevation compatible with theturbinecasing dimensions and the overall bearing alignment scheme. Thisallows various adjustable leveling devices, well known in the art, toposition each seating plate segment to support the turbine casings withan optimum distribution of normal forces on the seating plates.Previously, with the unitary seating plate, concentrated forces at theturbine casing foot 2a and at the vertical joints 35 and 36 would resultfrom any mismatch in elevation, and required expensive and timeconsuming hard finishing operations to preclude gouging of the seatingplate and subsequent misalignment problems.

Foundation anchor bolts, such as 37, are disposed all along thelongitudinal centerlines extending through all the segments of each ofthe seating plate groupings 4, 5 and 6.

To ensure cumulative expansion of the low pressure turbine units aboutthe point of fixity at the center of the low pressure turbine unit 2,push-pull tie beams 38 and 39 are secured to the foot area of theadjacent end casing base portions of the units 2 and 3 and similar beams40 and 41 are secured to the foot area of the adjacent end casing basesof units 1 and 2.

Variations may be made in the shape of the ends 21a and 22a of theanchor post 21 and 22, respectively, that is, they may be maderectangular or polygonal with corresponding shaped anchor bushings 24,instead of round as described.

Furthermore, the segmented seating plate construction described for thistandem arrangement of three low pressure turbines may be applied to anyother tandem or cross compound arrangement of low pressure turbines torealize similar benefits and advantages to those herein enumerated. Anadditional advantage of the present structure is that it considerablyreduces the required number of foundation anchor bolts resulting insavings on associated design details. Additionally, a major loadreduction occurs because, whereas in the existing or well known designdescribed above under Background of the Invention, the transverse anchordesign load results as a function of a differential friction force atthe seating plate-togrout interface in the present invention thetransverse anchor design load results as a function of a differentialfriction force at the turbine base-to-seating plate interface. Thelatter has an inherently lower coeffic'ient of friction as well as thecomplete absence of foundation anchor bolt clamping forces in the normalor vertical direction. This tends to reduce transverse anchor loads byabout one one-third.

Smaller plate sections will have the same relative movement to the groutdue to differential thermal expansion, but this movement will no longerbe cumulative, therefore, this should add measurably to stabilizing theturbine alignment throughout the operating life of the machinery.

Thus it is seen that a segmented seating plate structure with eccentricanchoring means is provided, which seating plate structure isunconnected, more reliable, less expensive, and which structure greatlyreduces the number of foundation anchor bolts because it is no longernecessary to use them to augment the friction stability forcespreviously described, and provides more aligning flexibility than ispresently available, Because of the increase in associated tolerances,the seating plates and turbine casings do not have to be prefittedbefore erection at the plant site and the eccentric anchors permiterection in less time than heretofore. Furthermore, the following areeliminated: welding and machining of dowel pinned and bolted lap jointsin adjacent sections of seating plates; heat treating seating plates;machining the lower surface of the seating plates thereby reducingfabrication thickness; and finishing operation to custom fit the turbinekeyways; the severe vertical tolerance limitation on turbine casings;and precise thickness matching at adjacent sections of seating plates.

Since numerous changes 'may be made in the abovedescribed constructionand differentembodiments of the invention may be made without departingfrom the spirit and scope thereof, it is intended that all subjectmatter contained in the foregoing description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:

l. A large machine subjected to substantial differential thermalexpansions between said machine and its foundation during operation,

said machine having a longitudinal centerline, a plane transverse tosaid longitudinal centerline and containing a transverse centerline ofsaid machine, and a base portion supported on a foundation,

seating plates supported by said foundation and frictionally engagingsaid base portion of said machine,

said seating plates comprising a plurality of separate unconnectedsegments, said segments including two opposed central segments havingtheir transverse centerlines extending along said transverse plane ofsaid machine,

anchoring means for anchoring each of said central segments to saidfoundation,

and means for securing said machine to said central segments to preventmovement of said machine in the longitudinal direction at said centralsegments.

2. The structure recited in claim 1 and further providing means forexpansion of the machine in a horizontal plane.

3. The structure recited in claim 2 wherein the means for providinghorizontal expansion and the means for securing the machine comprise twokeyways equally spaced on opposite sides of the longitudinal centerline,each keyway cooperatively defined by a central seating plate segment andthe machine base portion,

and a key disposed in each of said keyways.

4. The structure recited in claim 3 wherein the keyways and keys aredisposed in a horizontal plane, and are mutually normal to thelongitudinal centerline of the machine.

5. The structure recited in claim 1 wherein the anchoring means compriseat least one post embedded in the foundation,

each central segment defining at least one opening therein correspondingto said post,

said post extending upwardly into said corresponding opening in thecentral segment,

said post having a smaller cross-sectional dimension than said openingand thereby defining a gap.

and means for bridging said gap in said opening between said post andthe central segment to provide a rigid connection between the post andsegment.

6. The structure recited in claim 5 wherein the bridging means comprisesa bushing member which is fitted to the post, bridging the gap in theopening.

7. The structure recited in claim 1 wherein the anchoring means compriseat least one post embedded in the foundation,

each central segment defining at least one opening therein correspondingto said post,

said post extending upwardly into said corresponding opening in thecentral segment,

. said post having a smaller cross-sectional dimension than said openingand thereby defining a gap,

a means for bridging said gap in said opening between said post and thecentral segment to provide a rigid connection between said post andsegment,

said bridging means comprising a bushing member which is fitted onto thepost bridging the gap in the opening,

said post being eccentrically disposed in said opening and said bushingmember having a corresponding aperture which is eccentric with respectto its outer dimension.

8. The structure recited in claim 1 wherein the anchoring means compriseat least one post embedded in the foundation, each central segmentdefining at least one opening therein corresponding to said post,

said post extending upwardly into said corresponding opening in thecentral segment,

said post having a smaller cross-sectional dimension than said openingand jointly defining a gap therewith,

means for bridging said gap in said opening between said post and saidcentral segment, to provide a rigid connection between said post andsegment,

said bridging means comprising a bushing member which is fitted to thepost, bridging said gap in said opening,

said post being eccentrically disposed in said opening and said bushingmember having a corresponding aperture which is eccentric with respectto its outer dimension, and

said post, said opening and said bushing member being circular in crosssection.

9. The structure recited in claim 1 wherein the base portion of themachine is substantially rectangular in cross section and the seatingplate segments are arranged in a substantially rectangular configurationto support the machine.

10. The structure recited in claim 1 wherein the seating plate segmentsare rectangular in cross section.

11. The structure recited in claim 6 wherein the base portion of themachine has access apertures of greater dimension than the dimension ofthe bushing member, one of said apertures corresponding to each openingin the seating plate.

12. The structure recited in claim 6 wherein each bushing member and thefoundation are in spaced relation, and wherein a retaining washer issecured to the bottom of each central segment to assist in supportingthe bushing member.

formed of a plurality of housing units.

15. The structure recited in claim 14 wherein the units are turbinesheated by hot motive fluid which produces differential thermal expansionin the units.

1. A large machine subjected to substantial differential thermalexpansions between said machine and its foundation during operation,said machine having a longitudinal centerline, a plane transverse tosaid longitudinal centerline and containing a transverse centerline ofsaid machine, and a base portion supported on a foundation, seatingplates supported by said foundation and frictionally engaging said baseportion of said machine, said seating plates comprising a plurality ofseparate unconnected segments, said segments including two opposedcentral segments having their transverse centerlines extending alongsaid transverse plane of said machine, anchoring means for anchoringeach of said central segments to said foundation, and means for securingsaid machine to said central segments to prevent movement of saidmachine in the longitudinal direction at said central segments.
 2. Thestructure recited in claim 1 and further providing means for expansionof the machine in a horizontal plane.
 3. The structure recited in claim2 wherein the means for providing horizontal expansion and the means forsecuring the machine comprise two keyways equally spaced on oppositesides of the longitudinal centerline, each keyway cooperatively definedby a central seating plate segment and the machine base portion, and akey disposed in each of said keyways.
 4. The structure recited in claim3 wherein the keyways and keys are disposed in a horizontal plane, andare mutually normal to the longitudinal centerline of the machine. 5.The structure recited in claim 1 wherein the anchoring means comprise atleast one post embedded in the foundation, each central segment definingat least one opening therein corresponding to said post, said postextending upwardly into said corresponding opening in the centralsegment, said post having a smaller cross-sectional dimension than saidopening and thereby defining a gap, and means for bridging said gap insaid opening between said post and the central segment to provide arigid connection between the post and segment.
 6. The structure recitedin claim 5 wherein the bridging means comprises a bushing member whichis fitted to the post, bridging the gap in the opening.
 7. The structurerecited in claim 1 wherein the anchoring means comprise at least onepost embedded in the foundation, each central segment defining at leastone opening therein corresponding to said post, said Post extendingupwardly into said corresponding opening in the central segment, saidpost having a smaller cross-sectional dimension than said opening andthereby defining a gap, a means for bridging said gap in said openingbetween said post and the central segment to provide a rigid connectionbetween said post and segment, said bridging means comprising a bushingmember which is fitted onto the post bridging the gap in the opening,said post being eccentrically disposed in said opening and said bushingmember having a corresponding aperture which is eccentric with respectto its outer dimension.
 8. The structure recited in claim 1 wherein theanchoring means comprise at least one post embedded in the foundation,each central segment defining at least one opening therein correspondingto said post, said post extending upwardly into said correspondingopening in the central segment, said post having a smallercross-sectional dimension than said opening and jointly defining a gaptherewith, means for bridging said gap in said opening between said postand said central segment, to provide a rigid connection between saidpost and segment, said bridging means comprising a bushing member whichis fitted to the post, bridging said gap in said opening, said postbeing eccentrically disposed in said opening and said bushing memberhaving a corresponding aperture which is eccentric with respect to itsouter dimension, and said post, said opening and said bushing memberbeing circular in cross section.
 9. The structure recited in claim 1wherein the base portion of the machine is substantially rectangular incross section and the seating plate segments are arranged in asubstantially rectangular configuration to support the machine.
 10. Thestructure recited in claim 1 wherein the seating plate segments arerectangular in cross section.
 11. The structure recited in claim 6wherein the base portion of the machine has access apertures of greaterdimension than the dimension of the bushing member, one of saidapertures corresponding to each opening in the seating plate.
 12. Thestructure recited in claim 6 wherein each bushing member and thefoundation are in spaced relation, and wherein a retaining washer issecured to the bottom of each central segment to assist in supportingthe bushing member.
 13. The structure recited in claim 1 wherein a layerof grout is placed between the foundation and the seating plates andwherein each central segment is provided with anchor discs embedded insaid layer.
 14. The structure recited in claim 1 wherein the machine isformed of a plurality of housing units.
 15. The structure recited inclaim 14 wherein the units are turbines heated by hot motive fluid whichproduces differential thermal expansion in the units.